I don't know if you saw my response but all you need to do to help the user is to add some javascript that initially scrolls down after a few seconds, so the user gets the idea going down does something (stop the auto-scrolling when they scroll or use arrow keys). There are a lot of sites these days that "activate" when scrolled down, so even a hint that you can do that will make people say OH!

You could also just use the technique that Apple used on the Mac Pro page:

Small arrow at the bottom letting you know to scroll, and it also doubles as something that would get them to try the arrow keys. It also has small dots at the side to let you know your progress, though those might be too much. You could again remove the indicator when the user actually scrolls. Even that seems like too much though, I really like your gallery without clutter and I think the auto-scrolling would give that effect.

BTW one of the things I loved about your gallery was the speed and fluidity of it. That's why I am so against adding too many things to it because it works exactly as I would hope a web gallery would at the core of things.

thanks again Kendall,

I don't know Java script, but I will try to understand if I'm able to do something along your suggestion